1. Field of the Invention
This invention relates generally to sludge filtration systems for separating sludge solids from sludge liquids. More specifically, this invention relates to such systems which include at least one filter assembly through which vacuum filtration can be induced and whose filter assemblies are selectively slidably removable from their associated containers.
The removability of the filter assemblies from their associated containers enables the thorough and efficient cleaning of the system. In turn, the thorough and efficient cleaning of the system is critical for the continued proper operation of the system and for safety purposes. If the system, particularly the filtration elements of the system, are not cleaned, then solid matter may build up or become lodged thereon restricting the flow of filtrate through the filtration elements. In addition, some of the sludge introduced into the system may be hazardous to the health of operators. Thus, after use, such systems must be properly cleaned so that all hazardous sludge residue is adequately removed from the system, allowing the system to be safely used again.
2. Related Art
Sludge filtration systems are known to the prior art. Illustrative of such systems are this Applicant's own U.S. Pat. Nos. 5,595,654, 5,681,460, and 5,858,226. Also illustrative of such systems are U.S. Pat. Nos. 4,929,353, 5,589,081, and 5,707,535, each issued to Harris. None of the listed patents, however, includes mechanisms and/or methods which enable the efficient and easy removability of the filtration elements from the associated containers.
The majority of prior art systems do not include filtration elements that are easily removable from the container in which they are held. The cleaning of these systems must thus be performed with the filtration elements attached to the container. It has been found, however, that the inclusion of the filtration elements during the cleaning operation inhibits the adequate cleaning of all the elements of the system. This is particularly true for closed-in containers, or vacuum boxes, which include interiors that are not easily accessible to a person. Thus, it would be beneficial to the prior art to provide a sludge filtration system which includes filtration elements that are easily removable from their associated containers. In addition, it would be particularly beneficial to the prior art to provide a sludge filtration system that includes a vacuum box with filtration elements that are easily removable from the vacuum box.
Some of the sludge filtration systems in the prior art include filtration elements that may conceivably be removed from their containers. However, none of these systems include mechanisms or methods which enable and/or aid in the easy and efficient removability of the filtration elements from the containers. For instance, this Applicant's U.S. Pat. No. 5,681,460 teaches a Selectively Removable Sludge Filtration System and Method which in essence comprises a filter basket structure disposed within a container. In order to remove the System from the container, the System is either lifted out of the container (by use of a crane or the like) or the System is slid out of the container. Sliding the disclosed System out of the container may damage either the underside of the System or the container bottom. Likewise, Harris' U.S. Pat. Nos. 4,929,353 and 5,589,081 disclose basket-like filter structures that can be removed from their containers by either lifting or sliding them out of the disclosed container. Lifting the structures would require the use of a crane, a piece of equipment that is not owned by many users of sludge filtration systems. Sliding the structures out of their containers may damage either the underside of the structures or the container bottoms.
Furthermore, in any of the basket-like filtration elements of the prior art and since the disclosed containers stand a given distance from the ground, the sliding removal of the filtration elements eventually results in the filtration elements slamming to the ground, unless the filtration elements are somehow propped up prior to their complete removal from the container. It would thus be beneficial to the prior art to provide a sludge filtration system that includes mechanisms or methods which enable and/or aid in the easy and efficient removability of the filtration elements from the containers.
Moreover, as is known to those skilled in the art, two types of filtration exist: gravitational filtration and vacuum filtration. In gravitational filtration, the filtrate passes through the filtration element simply by the force of gravity. On the other hand, in vacuum filtration, the filtrate passes through the filtration element because a pressure differential has been created, usually by a suction pump, across the filtration element. Each type of filtration has its benefits and drawbacks. Thus, it would be beneficial to the prior art to provide a sludge filtration system that may be used to induce both vacuum filtration and gravitational filtration and that includes filtration elements that are easily removable from their associated containers.